Speaker
Dr
Stephen Magill
(Argonne National Laboratory)
Description
Many current and future elementary particle physics experiments require detection of light emitted in the UV wavelength range. This includes neutrino experiments in liquid Argon (128 nm scintillation) or water (~200 nm Cerenkov), dark matter and neutrinoless double beta decay experiments in gaseous or liquid Xenon (175 nm scintillation) and calorimetry with crystals in g-2 (PbF2 Cerenkov) and Mu2e (220 nm scintillation in BaF2) among others. Wavelength shifters must be used to convert the generated UV light into detectable wavelengths. Recently, by producing materials whose fundamental particle size is smaller than the electron wavelength in the material, the photo absorption and emission properties of the material can be modified to accommodate UV light detection with existing (visible-sensitive) photosensors. Sizes are typically required to be in the 1- 100 nm range, thus the label nanoparticles. A material nanoparticle in which all 3 spatial dimensions are smaller than the electron wavelength is called a “Quantum Dot”. Since the modified detection properties of nanoparticles result from changes in individual atoms or molecules, it is anticipated that light detection with nanoparticles is stronger, faster, and more efficient than bulk material wavelength shifters (e.g., TPB). At ANL, we have initiated testing of nanoparticle types with the goal of developing coatings and/or inserts that absorb a desired wavelength and then re-emit the absorbed energy in a longer wavelength tuned to the peak sensitivity of an existing selected photosensor. In all, about a dozen different nanoparticle types have been tested in several configurations - over half have shown response in the UV wavelength range with emission detectable by visible-sensitive silicon photomultiplier sensors. Applications are not limited to HEP experiments - other possibilities include enhanced vision in low light conditions and in interior spaces through windows and skylights, more efficient use of natural light for photosynthesis and extension of visible astronomy into the UV region to investigate e.g., galaxy formation.
Primary author
Dr
Stephen Magill
(Argonne National Laboratory)
